Third Window Syndrome: An Up-to-Date Systematic Review of Causes, Diagnosis, and Treatment

Third window syndrome (TWS) is an inner ear condition caused by an additional compliant point in the otic capsule that disrupts auditory and vestibular functions. Superior semicircular canal dehiscence is the most common cause, presenting with hearing loss, vertigo, and autophony, significantly impairing quality of life. This study evaluated the pathophysiology, diagnostics, treatments, and recent advancements in TWS while identifying research gaps. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 70 studies from Embase, MEDLINE, Cochrane, and UpToDate databases were analyzed. TWS affects inner ear mechanics, enhancing bone conduction and reducing air conduction. Diagnosis involves clinical evaluations, high-resolution imaging, and functional tests such as vestibular evoked myogenic potentials, which are known for their high sensitivity and specificity. Management strategies range from vestibular rehabilitation and pharmacotherapy to surgical interventions, including transmastoid and middle cranial fossa approaches, which achieve over 75% success. Emerging minimally invasive techniques, such as underwater endoscopic ear surgery and round window reinforcement, show promise but carry risks like cerebrospinal fluid leakage and inconsistent symptom relief. Advancements in TWS management have improved outcomes, yet gaps remain, particularly in terms of false-positive imaging and long-term efficacy. Future studies should prioritize predictive models and minimally invasive techniques. A multidisciplinary approach is essential to improve patient care.